/*---------------------------------------------------------------------------*\
  =========                 |
  \\      /  F ield         | OpenFOAM: The Open Source CFD Toolbox
   \\    /   O peration     |
    \\  /    A nd           | www.openfoam.com
     \\/     M anipulation  |
-------------------------------------------------------------------------------
    Copyright (C) 2017 OpenCFD Ltd.
-------------------------------------------------------------------------------
License
    This file is part of OpenFOAM.

    OpenFOAM is free software: you can redistribute it and/or modify it
    under the terms of the GNU General Public License as published by
    the Free Software Foundation, either version 3 of the License, or
    (at your option) any later version.

    OpenFOAM is distributed in the hope that it will be useful, but WITHOUT
    ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
    FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
    for more details.

    You should have received a copy of the GNU General Public License
    along with OpenFOAM.  If not, see <http://www.gnu.org/licenses/>.

Class
    Foam::cellCellStencils::leastSquares

Description
    Least-squares-weighted interpolation stencil.

    Base machinery is similar to inverse distance interpolation stencil
    but weights minimize error in LSQ sense recovering exact solution
    for linear solution problems. Gradient and values are found
    simultaneously.

SourceFiles
    leastSquaresCellCellStencil.C

\*---------------------------------------------------------------------------*/

#ifndef cellCellStencils_leastSquares_H
#define cellCellStencils_leastSquares_H

#include "inverseDistanceCellCellStencil.H"

// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //

namespace Foam
{

namespace cellCellStencils
{

/*---------------------------------------------------------------------------*\
                        Class leastSquares Declaration
\*---------------------------------------------------------------------------*/

class leastSquares
:
    public inverseDistance
{
    // Private Member Functions

        //- No copy construct
        leastSquares(const leastSquares&) = delete;

        //- No copy assignment
        void operator=(const leastSquares&) = delete;


public:

    //- Runtime type information
    TypeName("leastSquares");


    // Constructors

        //- Construct from fvMesh
        leastSquares(const fvMesh&, const dictionary&);


    //- Destructor
    virtual ~leastSquares();


    // Member Functions

        //- Calculate lsq weights for single acceptor
        virtual void stencilWeights
        (
            const point& sample,
            const pointList& donorCcs,
            scalarList& weights
        ) const;
};


// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //

} // End namespace cellCellStencils
} // End namespace Foam

// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //

#endif

// ************************************************************************* //
